As more people move to North Carolina, subdivisions push into tick country -- the rural and wooded areas around our urban centers. As a result, tick bites are more common. No hike through the woods required.

You can be bitten anytime, but the blood-sucking pests are most active between April and October.

"I check my kids every night," said Rhonda Houchens, a mother of two who says ticks are all over her North Raleigh neighborhood. "We get them in the yard. We've even gotten them at the [neighborhood] pool."

Entomologists say all that extra contact with ticks is the main reason Rocky Mountain spotted fever, the most common tick-borne disease, is surging in North Carolina. Last year, there were 625 cases in the state, up from 35 in 1997.

And this year, North Carolina had about 75 percent of all Rocky Mountain spotted fever cases reported nationally through April, according to the Centers for Disease Control and Prevention. Some of those cases occurred in late 2005 but weren't reported to the state until this year, which may have inflated those numbers, said Dr. Jeffrey Engel, the state epidemiologist.

Two other tick-borne illnesses -- Lyme disease and ehrlichiosis -- are also up in North Carolina, though to a lesser degree.

Growth and suburbanization, while major contributors, can't take all of the blame.

The state's burgeoning population of deer, and their increasing presence near homes, also plays a role, entomologists say. Parts of Wake, Orange and Durham counties now have 45 or more deer per square mile. That's on par with the most densely populated deer habitats in the state, according to the state Division of Wildlife Management.

Ticks hitch rides on deer and drop off in residential areas, where they prey on humans.

Nolan Newton, an entomologist with the state Department of Environment and Natural Resources, said deer are considered the main reason the lone star tick -- rarely found east of Interstate 95 until about a decade ago -- is now common across the Triangle and parts east. The lone star readily bites people and carries several diseases.

"You've got more deer and more ticks in close proximity with people, and as a result, more disease," Newton said.

Ticks are particularly dangerous now, in the spring, when many species are in their "nymph" stage and are so tiny they are nearly impossible to spot on the skin. A nymph is only about the size of a poppy seed.

Tick-borne illnesses, caused by bacteria passed through the tick's mouthparts, can have grave consequences without early treatment.

Rocky Mountain spotted fever -- which in its late stages causes a dark, mottled rash -- can be fatal if allowed to run its course. Before the discovery of tetracycline and other antibiotics in the late 1940s, up to 30 percent of people who contracted the dreaded "black measles" died from it.

Even today, despite the availability of inexpensive, effective treatment, Rocky Mountain spotted fever still kills up to 5 percent of patients, according to the CDC.

Patients often don't recognize early symptoms, which look a lot like those that accompany many cold and flu bugs. For the same reason, doctors can have a hard time diagnosing Rocky Mountain spotted fever -- which, despite its name, is most prevalent in the southeastern United States. As a result, most patients become so ill they are hospitalized.

It wasn't immediately clear that Samantha Felton of Raleigh, now 16, had Rocky Mountain spotted fever when she fell ill two summers ago, even though she had recently returned home from a four-day hiking trip over heavily wooded terrain where ticks had been a daily bother.

When her symptoms persisted for more than a day and her fever shot as high as 106 degrees, her parents took her to a doctor. It took a couple of days and a second visit to the doctor before one of the physicians asked whether Samantha might have been bitten by a tick.

"Pretty close to every night, I had to pull one off," she recalled.

Her doctor diagnosed a probable case of Rocky Mountain spotted fever and prescribed antibiotics, which cleared up her symptoms.

William Hite, 72, of Oxford never saw the tick that caused his high fever, body aches and extreme fatigue last summer. In fact, he never knew he'd been bitten. But after a blood test pointed to spotted fever, Hite went to the hospital, where he stayed about a week.

Hite said he had never noticed ticks in his yard, in the heart of Oxford. But a few weeks ago as he was standing in his driveway, a black, spotted tick dropped onto his arm, apparently from a tree limb. "He died right quick," Hite said.

Not all entomologists are convinced that spotted fever alone is to blame for North Carolina's rising tide of tick-borne illness.

Few doctors order the battery of complicated blood tests needed to confirm a diagnosis of Rocky Mountain spotted fever. Some lesser-known diseases such as ehrlichiosis and Southern tick-associated rash illness, or STARI, start with similar symptoms and respond to the same antibiotics.

"Every tick bite that comes into a doctor's office gets reported as Rocky Mountain spotted fever," said Charles Apperson, a professor of entomology at N.C. State University. "I think there may be some overreporting."